Such clutches or brakes are used for example in adjustment systems for camshafts of an internal combustion engine, which comprise a superposition transmission with a drive input element driven by a crankshaft of the internal combustion engine, with a drive output element that drives a camshaft of the internal combustion engine and with a control element by means of which, by applying a braking torque, relative rotation can be produced between the drive input element and the drive output element. However, electromagnetically actuated clutches or brakes can also be used as shifting elements in automatic transmissions, in order therein to couple rotating transmission components to one another or to brake them relative to a transmission housing.
DE 10 2006 011 806 A1 describes an adjustment device for a camshaft, which comprises a brake system and a superposition transmission connected on the output side to the camshaft and on the input side to the crankshaft, such that to adjust the camshaft the superposition transmission diverts part of the input-side energy into the brake system. The frictional brake system produces the necessary braking force by virtue of a friction lining which is permanently in a slipping condition, in that a switching coil on an armature, to which the friction lining is fixed, acts by virtue of electrical regulation and, depending on the necessary phase position, produces a corresponding braking torque. This adjustment device comprises additional, mechanical locking means which come into effect when the switching coil is not energized, in that the armature is pushed axially by a spring so that an adjustment shaft is connected with interlock to the drive input element of the superposition transmission. The switching coil is fixed onto the housing and needs to be adjusted relative to the armature with the friction lining which is arranged in a rotationally fixed manner and axially movably on the adjustment shaft.
DE 102 20 687 A1 describes a similar adjustment device, which also comprises a superposition transmission with a drive input element driven by a crankshaft of the internal combustion engine, a drive output element that drives a camshaft of the internal combustion engine, and a control element by which a relative rotation between the drive input and the drive output elements can be produced by virtue of an electric motor control drive that acts on the control element. In addition an electromagnetic brake is also provided between the control element and a fixed part of the housing, by means of which a basic or emergency position of the camshaft can be reached and held. This adjustment device for a camshaft is represented only schematically and it cannot be seen how the electric motor control drive and the electromagnetic brake are mounted relative to the housing part and the superposition transmission.